// This file is part of the FidelityFX SDK.
//
// Copyright (c) 2022 Advanced Micro Devices, Inc. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
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// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

#pragma once

#include "ffx_assert.h"
#include "ffx_types.h"
#include "ffx_error.h"

// Include the FSR2 resources defined in the HLSL code. This shared here to avoid getting out of sync.
#define FFX_CPU
#include "shaders/ffx_fsr2_resources.h"
#include "shaders/ffx_fsr2_common.h"


namespace Fsr212
{

#if defined(__cplusplus)
    extern "C" {
#endif // #if defined(__cplusplus)

        FFX_FORWARD_DECLARE(FfxFsr2Interface212);

        /// An enumeration of all the passes which constitute the FSR2 algorithm.
        ///
        /// FSR2 is implemented as a composite of several compute passes each
        /// computing a key part of the final result. Each call to the 
        /// <c><i>FfxFsr2ScheduleGpuJobFunc</i></c> callback function will
        /// correspond to a single pass included in <c><i>FfxFsr2Pass</i></c>. For a
        /// more comprehensive description of each pass, please refer to the FSR2
        /// reference documentation.
        ///
        /// Please note in some cases e.g.: <c><i>FFX_FSR2_PASS_ACCUMULATE</i></c>
        /// and <c><i>FFX_FSR2_PASS_ACCUMULATE_SHARPEN</i></c> either one pass or the
        /// other will be used (they are mutually exclusive). The choice of which will
        /// depend on the way the <c><i>FfxFsr2Context</i></c> is created and the
        /// precise contents of <c><i>FfxFsr2DispatchParamters</i></c> each time a call
        /// is made to <c><i>ffxFsr2ContextDispatch</i></c>.
        /// 
        /// @ingroup FSR2
        typedef enum FfxFsr2Pass {

            FFX_FSR2_PASS_PREPARE_INPUT_COLOR = 0,                              ///< A pass which prepares input colors for subsequent use.
            FFX_FSR2_PASS_DEPTH_CLIP = 1,                                       ///< A pass which performs depth clipping.
            FFX_FSR2_PASS_RECONSTRUCT_PREVIOUS_DEPTH = 2,                       ///< A pass which performs reconstruction of previous frame's depth.
            FFX_FSR2_PASS_LOCK = 3,                                             ///< A pass which calculates pixel locks.
            FFX_FSR2_PASS_ACCUMULATE = 4,                                       ///< A pass which performs upscaling.
            FFX_FSR2_PASS_ACCUMULATE_SHARPEN = 5,                               ///< A pass which performs upscaling when sharpening is used.
            FFX_FSR2_PASS_RCAS = 6,                                             ///< A pass which performs sharpening.
            FFX_FSR2_PASS_COMPUTE_LUMINANCE_PYRAMID = 7,                        ///< A pass which generates the luminance mipmap chain for the current frame.
            FFX_FSR2_PASS_GENERATE_REACTIVE = 8,                                ///< An optional pass to generate a reactive mask

            FFX_FSR2_PASS_COUNT                                                 ///< The number of passes performed by FSR2.
        } FfxFsr2Pass;

        /// Create and initialize the backend context.
        ///
        /// The callback function sets up the backend context for rendering.
        /// It will create or reference the device and create required internal data structures.
        ///
        /// @param [in] backendInterface                    A pointer to the backend interface.
        /// @param [in] device                              The FfxDevice obtained by ffxGetDevice(DX12/VK/...).
        ///
        /// @retval
        /// FFX_OK                                          The operation completed successfully.
        /// @retval
        /// Anything else                                   The operation failed.
        ///
        /// @ingroup FSR2
        typedef FfxErrorCode(*FfxFsr2CreateBackendContextFunc)(
            FfxFsr2Interface212* backendInterface,
            FfxDevice device);

        /// Get a list of capabilities of the device.
        ///
        /// When creating an <c><i>FfxFsr2Context</i></c> it is desirable for the FSR2
        /// core implementation to be aware of certain characteristics of the platform
        /// that is being targetted. This is because some optimizations which FSR2
        /// attempts to perform are more effective on certain classes of hardware than
        /// others, or are not supported by older hardware. In order to avoid cases
        /// where optimizations actually have the effect of decreasing performance, or
        /// reduce the breadth of support provided by FSR2, FSR2 queries the
        /// capabilities of the device to make such decisions.
        ///
        /// For target platforms with fixed hardware support you need not implement
        /// this callback function by querying the device, but instead may hardcore
        /// what features are available on the platform.
        ///
        /// @param [in] backendInterface                    A pointer to the backend interface.
        /// @param [out] outDeviceCapabilities              The device capabilities structure to fill out.
        /// @param [in] device                              The device to query for capabilities.
        ///
        /// @retval
        /// FFX_OK                                          The operation completed successfully.
        /// @retval
        /// Anything else                                   The operation failed.
        /// 
        /// @ingroup FSR2
        typedef FfxErrorCode(*FfxFsr2GetDeviceCapabilitiesFunc)(
            FfxFsr2Interface212* backendInterface,
            FfxDeviceCapabilities* outDeviceCapabilities,
            FfxDevice device);

        /// Destroy the backend context and dereference the device.
        ///
        /// This function is called when the <c><i>FfxFsr2Context</i></c> is destroyed.
        ///
        /// @param [in] backendInterface                    A pointer to the backend interface.
        ///
        /// @retval
        /// FFX_OK                                          The operation completed successfully.
        /// @retval
        /// Anything else                                   The operation failed.
        ///
        /// @ingroup FSR2
        typedef FfxErrorCode(*FfxFsr2DestroyBackendContextFunc)(
            FfxFsr2Interface212* backendInterface);

        /// Create a resource.
        ///
        /// This callback is intended for the backend to create internal resources.
        ///
        /// Please note: It is also possible that the creation of resources might
        /// itself cause additional resources to be created by simply calling the
        /// <c><i>FfxFsr2CreateResourceFunc</i></c> function pointer again. This is
        /// useful when handling the initial creation of resources which must be
        /// initialized. The flow in such a case would be an initial call to create the
        /// CPU-side resource, another to create the GPU-side resource, and then a call
        /// to schedule a copy render job to move the data between the two. Typically
        /// this type of function call flow is only seen during the creation of an
        /// <c><i>FfxFsr2Context</i></c>.
        ///
        /// @param [in] backendInterface                    A pointer to the backend interface.
        /// @param [in] createResourceDescription           A pointer to a <c><i>FfxCreateResourceDescription</i></c>.
        /// @param [out] outResource                        A pointer to a <c><i>FfxResource</i></c> object.
        ///
        /// @retval
        /// FFX_OK                                          The operation completed successfully.
        /// @retval
        /// Anything else                                   The operation failed.
        /// 
        /// @ingroup FSR2
        typedef FfxErrorCode(*FfxFsr2CreateResourceFunc)(
            FfxFsr2Interface212* backendInterface,
            const FfxCreateResourceDescription* createResourceDescription,
            FfxResourceInternal* outResource);

        /// Register a resource in the backend for the current frame.
        ///
        /// Since FSR2 and the backend are not aware how many different
        /// resources will get passed to FSR2 over time, it's not safe 
        /// to register all resources simultaneously in the backend.
        /// Also passed resources may not be valid after the dispatch call.
        /// As a result it's safest to register them as FfxResourceInternal 
        /// and clear them at the end of the dispatch call.
        ///
        /// @param [in] backendInterface                    A pointer to the backend interface.
        /// @param [in] inResource                          A pointer to a <c><i>FfxResource</i></c>.
        /// @param [out] outResource                        A pointer to a <c><i>FfxResourceInternal</i></c> object.
        ///
        /// @retval
        /// FFX_OK                                          The operation completed successfully.
        /// @retval
        /// Anything else                                   The operation failed.
        /// 
        /// @ingroup FSR2
        typedef FfxErrorCode(*FfxFsr2RegisterResourceFunc)(
            FfxFsr2Interface212* backendInterface,
            const FfxResource* inResource,
            FfxResourceInternal* outResource);

        /// Unregister all temporary FfxResourceInternal from the backend.
        ///
        /// Unregister FfxResourceInternal referencing resources passed to 
        /// a function as a parameter.
        ///
        /// @param [in] backendInterface                    A pointer to the backend interface.
        ///
        /// @retval
        /// FFX_OK                                          The operation completed successfully.
        /// @retval
        /// Anything else                                   The operation failed.
        /// 
        /// @ingroup FSR2
        typedef FfxErrorCode(*FfxFsr2UnregisterResourcesFunc)(
            FfxFsr2Interface212* backendInterface);

        /// Retrieve a <c><i>FfxResourceDescription</i></c> matching a
        /// <c><i>FfxResource</i></c> structure. 
        ///
        /// @param [in] backendInterface                    A pointer to the backend interface.
        /// @param [in] resource                            A pointer to a <c><i>FfxResource</i></c> object.
        ///
        /// @returns
        /// A description of the resource.
        ///
        /// @ingroup FSR2
        typedef FfxResourceDescription(*FfxFsr2GetResourceDescriptionFunc)(
            FfxFsr2Interface212* backendInterface,
            FfxResourceInternal resource);

        /// Destroy a resource
        ///
        /// This callback is intended for the backend to release an internal resource.
        ///
        /// @param [in] backendInterface                    A pointer to the backend interface.
        /// @param [in] resource                            A pointer to a <c><i>FfxResource</i></c> object.
        /// 
        /// @retval
        /// FFX_OK                                          The operation completed successfully.
        /// @retval
        /// Anything else                                   The operation failed.
        /// 
        /// @ingroup FSR2
        typedef FfxErrorCode(*FfxFsr2DestroyResourceFunc)(
            FfxFsr2Interface212* backendInterface,
            FfxResourceInternal resource);

        /// Create a render pipeline.
        ///
        /// A rendering pipeline contains the shader as well as resource bindpoints
        /// and samplers.
        /// 
        /// @param [in] backendInterface                    A pointer to the backend interface.
        /// @param [in] pass                                The identifier for the pass.
        /// @param [in] pipelineDescription                 A pointer to a <c><i>FfxPipelineDescription</i></c> describing the pipeline to be created.
        /// @param [out] outPipeline                        A pointer to a <c><i>FfxPipelineState</i></c> structure which should be populated.
        /// 
        /// @retval
        /// FFX_OK                                          The operation completed successfully.
        /// @retval
        /// Anything else                                   The operation failed.
        /// 
        /// @ingroup FSR2
        typedef FfxErrorCode(*FfxFsr2CreatePipelineFunc)(
            FfxFsr2Interface212* backendInterface,
            FfxFsr2Pass pass,
            const FfxPipelineDescription* pipelineDescription,
            FfxPipelineState* outPipeline);

        /// Destroy a render pipeline.
        ///
        /// @param [in] backendInterface                    A pointer to the backend interface.
        /// @param [out] pipeline                           A pointer to a <c><i>FfxPipelineState</i></c> structure which should be released.
        /// 
        /// @retval
        /// FFX_OK                                          The operation completed successfully.
        /// @retval
        /// Anything else                                   The operation failed.
        /// 
        /// @ingroup FSR2
        typedef FfxErrorCode(*FfxFsr2DestroyPipelineFunc)(
            FfxFsr2Interface212* backendInterface,
            FfxPipelineState* pipeline);

        /// Schedule a render job to be executed on the next call of
        /// <c><i>FfxFsr2ExecuteGpuJobsFunc</i></c>.
        ///
        /// Render jobs can perform one of three different tasks: clear, copy or
        /// compute dispatches.
        ///
        /// @param [in] backendInterface                    A pointer to the backend interface.
        /// @param [in] job                                 A pointer to a <c><i>FfxGpuJobDescription</i></c> structure.
        /// 
        /// @retval
        /// FFX_OK                                          The operation completed successfully.
        /// @retval
        /// Anything else                                   The operation failed.
        /// 
        /// @ingroup FSR2
        typedef FfxErrorCode(*FfxFsr2ScheduleGpuJobFunc)(
            FfxFsr2Interface212* backendInterface,
            const FfxGpuJobDescription* job);

        /// Execute scheduled render jobs on the <c><i>comandList</i></c> provided.
        /// 
        /// The recording of the graphics API commands should take place in this
        /// callback function, the render jobs which were previously enqueued (via
        /// callbacks made to <c><i>FfxFsr2ScheduleGpuJobFunc</i></c>) should be
        /// processed in the order they were received. Advanced users might choose to
        /// reorder the rendering jobs, but should do so with care to respect the
        /// resource dependencies.
        /// 
        /// Depending on the precise contents of <c><i>FfxFsr2DispatchDescription</i></c> a
        /// different number of render jobs might have previously been enqueued (for
        /// example if sharpening is toggled on and off).
        /// 
        /// @param [in] backendInterface                    A pointer to the backend interface.
        /// @param [in] commandList                         A pointer to a <c><i>FfxCommandList</i></c> structure.
        /// 
        /// @retval
        /// FFX_OK                                          The operation completed successfully.
        /// @retval
        /// Anything else                                   The operation failed.
        /// 
        /// @ingroup FSR2
        typedef FfxErrorCode(*FfxFsr2ExecuteGpuJobsFunc)(
            FfxFsr2Interface212* backendInterface,
            FfxCommandList commandList);

        /// A structure encapsulating the interface between the core implentation of
        /// the FSR2 algorithm and any graphics API that it should ultimately call.
        /// 
        /// This set of functions serves as an abstraction layer between FSR2 and the
        /// API used to implement it. While FSR2 ships with backends for DirectX12 and
        /// Vulkan, it is possible to implement your own backend for other platforms or
        /// which sits ontop of your engine's own abstraction layer. For details on the
        /// expectations of what each function should do you should refer the
        /// description of the following function pointer types:
        /// 
        ///     <c><i>FfxFsr2CreateDeviceFunc</i></c>
        ///     <c><i>FfxFsr2GetDeviceCapabilitiesFunc</i></c>
        ///     <c><i>FfxFsr2DestroyDeviceFunc</i></c>
        ///     <c><i>FfxFsr2CreateResourceFunc</i></c>
        ///     <c><i>FfxFsr2GetResourceDescriptionFunc</i></c>
        ///     <c><i>FfxFsr2DestroyResourceFunc</i></c>
        ///     <c><i>FfxFsr2CreatePipelineFunc</i></c>
        ///     <c><i>FfxFsr2DestroyPipelineFunc</i></c>
        ///     <c><i>FfxFsr2ScheduleGpuJobFunc</i></c>
        ///     <c><i>FfxFsr2ExecuteGpuJobsFunc</i></c>
        ///
        /// Depending on the graphics API that is abstracted by the backend, it may be
        /// required that the backend is to some extent stateful. To ensure that
        /// applications retain full control to manage the memory used by FSR2, the
        /// <c><i>scratchBuffer</i></c> and <c><i>scratchBufferSize</i></c> fields are
        /// provided. A backend should provide a means of specifying how much scratch
        /// memory is required for its internal implementation (e.g: via a function
        /// or constant value). The application is that responsible for allocating that
        /// memory and providing it when setting up the FSR2 backend. Backends provided
        /// with FSR2 do not perform dynamic memory allocations, and instead
        /// suballocate all memory from the scratch buffers provided.
        ///
        /// The <c><i>scratchBuffer</i></c> and <c><i>scratchBufferSize</i></c> fields
        /// should be populated according to the requirements of each backend. For
        /// example, if using the DirectX 12 backend you should call the 
        /// <c><i>ffxFsr2GetScratchMemorySizeDX12</i></c> function. It is not required
        /// that custom backend implementations use a scratch buffer.
        ///
        /// @ingroup FSR2
        typedef struct FfxFsr2Interface212 {

            FfxFsr2CreateBackendContextFunc         fpCreateBackendContext;         ///< A callback function to create and initialize the backend context.
            FfxFsr2GetDeviceCapabilitiesFunc        fpGetDeviceCapabilities;        ///< A callback function to query device capabilites.
            FfxFsr2DestroyBackendContextFunc        fpDestroyBackendContext;        ///< A callback function to destroy the backendcontext. This also dereferences the device.
            FfxFsr2CreateResourceFunc               fpCreateResource;               ///< A callback function to create a resource.
            FfxFsr2RegisterResourceFunc             fpRegisterResource;             ///< A callback function to register an external resource.
            FfxFsr2UnregisterResourcesFunc          fpUnregisterResources;          ///< A callback function to unregister external resource.
            FfxFsr2GetResourceDescriptionFunc       fpGetResourceDescription;       ///< A callback function to retrieve a resource description.
            FfxFsr2DestroyResourceFunc              fpDestroyResource;              ///< A callback function to destroy a resource.
            FfxFsr2CreatePipelineFunc               fpCreatePipeline;               ///< A callback function to create a render or compute pipeline.
            FfxFsr2DestroyPipelineFunc              fpDestroyPipeline;              ///< A callback function to destroy a render or compute pipeline.
            FfxFsr2ScheduleGpuJobFunc               fpScheduleGpuJob;               ///< A callback function to schedule a render job.
            FfxFsr2ExecuteGpuJobsFunc               fpExecuteGpuJobs;               ///< A callback function to execute all queued render jobs.

            void* scratchBuffer;                  ///< A preallocated buffer for memory utilized internally by the backend.
            size_t                                  scratchBufferSize;              ///< Size of the buffer pointed to by <c><i>scratchBuffer</i></c>.
        } FfxFsr2Interface;

#if defined(__cplusplus)
    }
#endif // #if defined(__cplusplus)
}